codekingpro/portable-devtools

1'use strict'
2
3const { LRUCache } = require('lru-cache')
4const dns = require('dns')
5
6// this is a factory so that each request can have its own opts (i.e. ttl)
7// while still sharing the cache across all requests
8const cache = new LRUCache({ max: 50 })
9
10const getOptions = ({
11  family = 0,
12  hints = dns.ADDRCONFIG,
13  all = false,
14  verbatim = undefined,
15  ttl = 5 * 60 * 1000,
16  lookup = dns.lookup,
17}) => ({
18  // hints and lookup are returned since both are top level properties to (net|tls).connect
19  hints,
20  lookup: (hostname, ...args) => {
21    const callback = args.pop() // callback is always last arg
22    const lookupOptions = args[0] ?? {}
23
24    const options = {
25      family,
26      hints,
27      all,
28      verbatim,
29      ...(typeof lookupOptions === 'number' ? { family: lookupOptions } : lookupOptions),
30    }
31
32    const key = JSON.stringify({ hostname, ...options })
33
34    if (cache.has(key)) {
35      const cached = cache.get(key)
36      return process.nextTick(callback, null, ...cached)
37    }
38
39    lookup(hostname, options, (err, ...result) => {
40      if (err) {
41        return callback(err)
42      }
43
44      cache.set(key, result, { ttl })
45      return callback(null, ...result)
46    })
47  },
48})
49
50module.exports = {
51  cache,
52  getOptions,
53}
54